[Devel] [RFC PATCH vz9 v6 30/62] dm-ploop: BAT use only one list for writeback

[Andrey Zhadchenko]

This should be merged into previous patches with writeback.

On 12/5/24 22:56, Alexander Atanasov wrote:
> remove the wb_batch_list_prio, use only wb_batch_list and
> use the md high_prio flag for immediate submission.
> 
> https://virtuozzo.atlassian.net/browse/VSTOR-91817
> Signed-off-by: Alexander Atanasov <alexander.atanasov at virtuozzo.com>
> ---
>   drivers/md/dm-ploop-map.c    | 70 +++++++++++++++---------------------
>   drivers/md/dm-ploop-target.c |  1 -
>   drivers/md/dm-ploop.h        |  1 -
>   3 files changed, 29 insertions(+), 43 deletions(-)
> 
> diff --git a/drivers/md/dm-ploop-map.c b/drivers/md/dm-ploop-map.c
> index 55c10d21d8eb..4d64c98d2bc1 100644
> --- a/drivers/md/dm-ploop-map.c
> +++ b/drivers/md/dm-ploop-map.c
> @@ -577,10 +577,6 @@ static void ploop_md_up_prio(struct ploop *ploop, struct md_page *md)
>   
>   	md->high_prio = true;
>   	WARN_ON_ONCE(!test_bit(MD_DIRTY, &md->status));
> -
> -	list_del(&md->wb_link);
> -	list_add(&md->wb_link, &ploop->wb_batch_list_prio);
> -
>   out:
>   	write_unlock_irqrestore(&ploop->bat_rwlock, flags);
>   }
> @@ -1817,43 +1813,41 @@ static void ploop_process_resubmit_pios(struct ploop *ploop,
>   	}
>   }
>   
> -static void ploop_submit_metadata_writeback_from_list(struct ploop *ploop,
> -						      struct list_head *list)
> +static void ploop_submit_metadata_writeback(struct ploop *ploop)
>   {
> -	struct md_page *md;
> +	ktime_t ktime, ktimeout;
> +	LIST_HEAD(ll_skipped);
> +	struct md_page *md, *mtmp;
> +	int send_all;
>   
> -	while (1) {
> +	ktime = ktime_get();
> +	ktimeout = ktime_add_ms(ktime, ploop->md_submit_delay_ms);
> +	send_all = ktime_after(ktime, ktimeout);
> +	/*
> +	 * Pages are set dirty so no one must touch lists
> +	 * if new md entries are dirtied they are added at the start of the list
> +	 */
> +	list_for_each_entry_safe(md, mtmp, &ploop->wb_batch_list, wb_link) {
>   		write_lock_irq(&ploop->bat_rwlock);
> -		md = list_first_entry_or_null(list, struct md_page, wb_link);
> -		if (!md) {
> +		list_del_init(&md->wb_link);
> +		if (md->high_prio || send_all) {
> +			/* L1L2 mustn't be redirtyed, when wb in-flight! */
> +			WARN_ON_ONCE(!test_bit(MD_DIRTY, &md->status));
> +			WARN_ON_ONCE(test_bit(MD_WRITEBACK, &md->status));
> +			set_bit(MD_WRITEBACK, &md->status);
> +			clear_bit(MD_DIRTY, &md->status);
> +			md->high_prio = false;
> +			write_unlock_irq(&ploop->bat_rwlock);
> +			ploop_index_wb_submit(ploop, md->piwb);
> +		} else {
> +			list_add_tail(&md->wb_link, &ll_skipped);
>   			write_unlock_irq(&ploop->bat_rwlock);
> -			break;
>   		}
> -		list_del_init(&md->wb_link);
> -		/* L1L2 mustn't be redirtyed, when wb in-flight! */
> -
> -		WARN_ON_ONCE(!test_bit(MD_DIRTY, &md->status));
> -		WARN_ON_ONCE(test_bit(MD_WRITEBACK, &md->status));
> -		set_bit(MD_WRITEBACK, &md->status);
> -		clear_bit(MD_DIRTY, &md->status);
> -		md->high_prio = false;
> -		write_unlock_irq(&ploop->bat_rwlock);
> -
> -		ploop_index_wb_submit(ploop, md->piwb);
>   	}
> -}
> -
> -static void ploop_submit_metadata_writeback(struct ploop *ploop)
> -{
> -	ktime_t time;
> -
> -	ploop_submit_metadata_writeback_from_list(ploop, &ploop->wb_batch_list_prio);
> +	write_lock_irq(&ploop->bat_rwlock);
> +	list_splice(&ll_skipped, &ploop->wb_batch_list);
> +	write_unlock_irq(&ploop->bat_rwlock);
>   
> -	time = ktime_get();
> -	if (ktime_after(time, ktime_add_ms(ploop->last_md_submit, ploop->md_submit_delay_ms))) {
> -		ploop->last_md_submit = time;
> -		ploop_submit_metadata_writeback_from_list(ploop, &ploop->wb_batch_list);
> -	}
>   }
>   
>   static void process_ploop_fsync_work(struct ploop *ploop, struct llist_node *llflush_pios)
> @@ -2009,16 +2003,10 @@ static void ploop_prepare_flush(struct ploop *ploop, struct pio *pio)
>   
>   	write_lock_irq(&ploop->bat_rwlock);
>   
> -	list_for_each_entry(md, &ploop->wb_batch_list_prio, wb_link) {
> -		md_inflight++;
> -		md->piwb->flush_pio = flush_pio;
> -	}
> -
>   	list_for_each_entry_safe(md, n, &ploop->wb_batch_list, wb_link) {
>   		md_inflight++;
>   		md->piwb->flush_pio = flush_pio;
> -		list_del(&md->wb_link);
> -		list_add_tail(&md->wb_link, &ploop->wb_batch_list_prio);
> +		md->high_prio = true;
>   	}
>   
>   	atomic_set(&flush_pio->md_inflight, md_inflight);
> diff --git a/drivers/md/dm-ploop-target.c b/drivers/md/dm-ploop-target.c
> index 67e3719c9378..0b691ff031e2 100644
> --- a/drivers/md/dm-ploop-target.c
> +++ b/drivers/md/dm-ploop-target.c
> @@ -438,7 +438,6 @@ static int ploop_ctr(struct dm_target *ti, unsigned int argc, char **argv)
>   	INIT_LIST_HEAD(&ploop->cluster_lk_list);
>   	init_llist_head(&ploop->wb_batch_llist);
>   	INIT_LIST_HEAD(&ploop->wb_batch_list);
> -	INIT_LIST_HEAD(&ploop->wb_batch_list_prio);
>   	ploop->last_md_submit = 0;
>   	ploop->md_submit_delay_ms = PLOOP_DEFAULT_METADATA_SUBMIT_DELAY;
>   
> diff --git a/drivers/md/dm-ploop.h b/drivers/md/dm-ploop.h
> index 0851b99c2ec6..e4dd7f382896 100644
> --- a/drivers/md/dm-ploop.h
> +++ b/drivers/md/dm-ploop.h
> @@ -179,7 +179,6 @@ struct ploop {
>   
>   	struct llist_head wb_batch_llist;
>   	struct list_head wb_batch_list;
> -	struct list_head wb_batch_list_prio;
>   
>   	ktime_t last_md_submit;
>   #define PLOOP_DEFAULT_METADATA_SUBMIT_DELAY 10000